1. Field of the Invention
The present invention relates to an antenna device, more particularly to Multiple-Input-Multiple-Output (MIMO) antenna device.
2. Description of the Related Art
U.S. Patent Application Publication Nos. 20060109067 and 20060192720 disclose two conventional smart array antenna systems, each of which includes a plurality of printed dipole antenna units that are large in dimensions and that are coupled to a single Radio Frequency (RF) port via a network comprising transmission cables, phase shifters, and power dividers. Such arrangement of the smart array antenna system, the network, and the RF port causes the printed dipole antenna units of the smart array antenna system to be unable to operate independently. The conventional smart array antenna systems are therefore unable to achieve maximum data rates between 450 Mbps and 600 Mbps (802.11n standard), and only conform to the specifications of the 802.11a/b/g standards. Consequently, wireless access points or wireless routers that employ the conventional smart array antenna systems cannot utilize the Multiple-Input-Multiple-Output (MIMO) technique for increased throughput.
Hence, there is a need in the art to provide a MIMO antenna system that can be installed inside wireless access points or wireless routers, and that includes antenna units adapted to operate independently so as to increase transmission throughput by utilizing the MIMO technique such that the MIMO antenna system conforms with the 802.11a/b/g/n standards.